<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        span {
            width: 100px;
            height: 100px;
            background-color: #f00;

            /* 实现元素之间的相互转化   display:block / inline / inline-block */
            display: inline-block;
            margin-top: 50px;
        }
    </style>
</head>

<body>

    <span></span>
    <span></span>
</body>

</html>